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Background This study represents a prospective, multicenter, open-label study to assess the safety, performance, and outcomes of poly-4-hydroxybutyrate (P4HB, Phasix™) mesh for primary ventral, primary incisional, or multiply-recurrent hernia in subjects at risk for complications. This study reports 3-year clinical outcomes. Materials and methods P4HB mesh was implanted in 121 patients via retrorectus or onlay technique. Physical exam and/or quality of life surveys were completed at 1, 3, 6,12, 18, 24, and 36 months, with 5-year (60-month) follow-up ongoing. Results A total of n = 121 patients were implanted with P4HB mesh (n = 75 (62%) female) with a mean age of 54.7 ± 12.0 years and mean BMI of 32.2 ± 4.5 kg/m2 (±standard deviation). Comorbidities included: obesity (78.5%), active smokers (23.1%), COPD (28.1%), diabetes mellitus (33.1%), immunosuppression (8.3%), coronary artery disease (21.5%), chronic corticosteroid use (5.0%), hypo-albuminemia (2.5%), advanced age (5.0%), and renal insufficiency (0.8%). Hernias were repaired via retrorectus (n = 45, 37.2% with myofascial release (MR) or n = 43, 35.5% without MR), onlay (n = 8, 6.6% with MR or n = 24, 19.8% without MR), or not reported (n = 1, 0.8%). 82 patients (67.8%) completed 36-month follow-up. 17 patients (17.9% ± 0.4%) experienced hernia recurrence at 3 years, with n = 9 in the retrorectus group and n = 8 in the onlay group. SSI (n = 11) occurred in 9.3% ± 0.03% of patients. Conclusions Long-term outcomes following ventral hernia repair with P4HB mesh demonstrate low recurrence rates at 3-year (36-month) postoperative time frame with no patients developing late mesh complications or requiring mesh removal. 5-year (60-month) follow-up is ongoing., Highlights • Prospective, multicenter, open-label study of safety, performance, and outcomes. • Poly-4-hydroxybutyrate mesh implanted in n = 121 patients via retrorectus or onlay. • 82 patients (67.8%) completed 36-month follow-up. • Hernia recurrence (n = 17, 17.9% ± 0.4%) and SSI (n = 11, 9.3% ± 0.03%) at 3 years. • No patients developed late mesh complications or required mesh removal.

Pressure ulcers are increasingly prevalent in an aging population. The most commonly used method of pressure ulcer prevention is pressure off-loading achieved by physically turning bedbound patients or by using expensive, single application devices such as wheelchair cushions. Our aim is to approach the problem of pressure ulcer prevention in a new way: a wireless sensor worn by the patient at locations susceptible to pressure injury. The sensor will monitor local pressure over time and transmits the data wirelessly to a base station (in a hospital setting) or smartphone (for home care). When a condition that would be harmful to tissue is reached, an alert would enable immediate direct intervention to prevent development of a pressure ulcer. The goal of this study was to validate the sensor's use in a live animal model and to lay the foundation for building time-pressure curves to predict the probability of pressure injury. Sprague-Dawley rats underwent surgical implantation of bilateral steel discs deep to the latissimus dorsi muscles. After the animals recovered from the surgical procedure, pressure was applied to the overlying tissue using magnets of varying strengths (30-150 mm Hg) for between 1 and 8 hours. Our sensor was placed on the skin prior to magnet application to wirelessly collect data regarding pressure and time. Three days after pressure application, animals were killed, injuries were graded clinically, and biopsies were collected for histological analysis. Results reveal that all animals with magnet application for more than 2 hours had clinical evidence of ulceration. Similarly, histological findings of hemorrhage were associated with increased time of pressure application. However, at high pressures (120-150 mm Hg), there were ischemic changes within the muscular layer without corresponding skin ulceration. We have developed a wireless sensor that can be placed on any at-risk area of the body and has the potential to alert caregivers when patients are at risk of developing a pressure injury. Our sensor successfully transmitted pressure readings wirelessly in a live, mobile animal. Future studies will focus on safety and efficacy with human use and development of algorithms to predict the probability of pressure ulcer formation.

Chronic wounds affect 6.5 million Americans, are complex conditions to manage and cost $28–$32 billion annually. Although digital solutions exist for non-expert clinicians to accurately segment tissues, analyze affected tissues or efficiently document their wound assessment results, there exists a lack of decision support for non-expert clinicians who usually provide most wound assessments and care decisions at the point of care (POC). We designed a machine learning (ML) system that can accurately predict wound care decisions based on labeled wound image data. The care decisions we predict are based on guidelines for standard wound care and are labeled as: continue the treatment, request a change in treatment, or refer patient to a specialist. In this paper, we demonstrate how our final ML solution using XGboost (XGB) algorithm achieved on average an overall performance of F-1 = .782 using labels given by an expert and a novice decision maker. The key contribution of our research lies in the ability of the ML artifact to use only those wound features (predictors) that require less expertise for novice users when examining wounds to make standard of care decisions (predictions).

With an aging population, the incidence and prevalence of wound problems is on the rise. Bedsores (also known as pressure ulcers or decubitus ulcers) are painful, take months to heal, and, for many patients, never do, leading to other health problems. The condition has become so acute that treating bedsores is now a significant burden on the healthcare system. An estimated 2.5 million pressure ulcers are treated in U.S. hospitals each year, adding US$11 billion annually to health care costs.

Long-term resorbable mesh represents a promising technology for complex ventral and incisional hernia repair (VIHR). Preclinical studies indicate that poly-4-hydroxybutyrate (P4HB) resorbable mesh supports strength restoration of the abdominal wall. This study evaluated outcomes of high-risk subjects undergoing VIHR with P4HB mesh. This was a prospective, multi-institutional study of subjects undergoing retrorectus or onlay VIHR. Inclusion criteria were CDC Class I, defect 10–350 cm2, ≤ 3 prior repairs, and ≥ 1 high-risk criteria (obesity (BMI: 30–40 kg/m2), active smoker, COPD, diabetes, immunosuppression, coronary artery disease, chronic corticosteroid use, hypoalbuminemia, advanced age, and renal insufficiency). Physical exam and/or quality of life surveys were performed at regular intervals through 18 months (to date) with longer-term, 36-month follow-up ongoing. One hundred and twenty-one subjects (46M, 75F) with an age of 54.7 ± 12.0 years and BMI of 32.2 ± 4.5 kg/m2 (mean ± SD), underwent VIHR. Comorbidities included the following: obesity (n = 95, 78.5%), hypertension (n = 72, 59.5%), cardiovascular disease (n = 42, 34.7%), diabetes (n = 40, 33.1%), COPD (n = 34, 28.1%), malignancy (n = 30, 24.8%), active smoker (n = 28, 23.1%), immunosuppression (n = 10, 8.3%), chronic corticosteroid use (n = 6, 5.0%), advanced age (n = 6, 5.0%), hypoalbuminemia (n = 3, 2.5%), and renal insufficiency (n = 1, 0.8%). Hernia types included the following: primary ventral (n = 17, 14%), primary incisional (n = 54, 45%), recurrent ventral (n = 15, 12%), and recurrent incisional hernia (n = 35, 29%). Defect and mesh size were 115.7 ± 80.6 and 580.9 ± 216.1 cm2 (mean ± SD), respectively. Repair types included the following: retrorectus (n = 43, 36%), retrorectus with additional myofascial release (n = 45, 37%), onlay (n = 24, 20%), and onlay with additional myofascial release (n = 8, 7%). 95 (79%) subjects completed 18-month follow-up to date. Postoperative wound infection, seroma requiring intervention, and hernia recurrence occurred in 11 (9%), 7 (6%), and 11 (9%) subjects, respectively. High-risk VIHR with P4HB mesh demonstrated positive outcomes and low incidence of hernia recurrence at 18 months. Longer-term 36-month follow-up is ongoing.

OBJECTIVE Rises in the incidence of pressure ulcers are increasingly prevalent in an aging population. Pressure ulcers are painful, are associated with increased morbidity and mortality, increase the risk for secondary infections and inpatient stay, and adds $26.8 billion annually to the healthcare costs of the USA. Evidence suggests that a change in the bioimpedance of living tissue in response to continuous local contact pressure can be a useful indicator for the onset of pressure injuries. APPROACH Thirty-five Sprague Dawley rats were subjected to various skin pressures for differing periods of time via a surgically inserted steel disk and an externally applied magnet. Contact pressure and bioimpedance were measured and correlated with tissue loading intensity and compared to clinical ulcer grading. MAIN RESULTS Moderate relationships between bioimpedance changes and tissue loading intensity were found. Stronger correlations were found by utilizing a combination of bioimpedance and phase angle. Thresholds were applied to the bioimpedance parameters and the usefulness of bioimpedance in classifying different ulcer stages is demonstrated. SIGNIFICANCE These results indicate that bioimpedance may be useful as an early indicator of pressure ulcer formation and has practical significance in the development of early pressure injury detection devices.

Lower extremity chronic wounds affect 4.5 million Americans annually. Due to inadequate access to wound experts in underserved areas, many patients receive non-uniform, non-standard wound care, resulting in increased costs and lower quality of life. We explored machine learning classifiers to generate actionable wound care decisions about four chronic wound types (diabetic foot, pressure, venous, and arterial ulcers). These decisions (target classes) were: (1) Continue current treatment, (2) Request non-urgent change in treatment from a wound specialist, (3) Refer patient to a wound specialist. We compare classification methods (single classifiers, bagged & boosted ensembles, and a deep learning network) to investigate (1) whether visual wound features are sufficient for generating a decision and (2) whether adding unstructured text from wound experts increases classifier accuracy. Using 205 wound images, the Gradient Boosted Machine (XGBoost) outperformed other methods when using both visual and textual wound features, achieving 81% accuracy. Using only visual features decreased the accuracy to 76%, achieved by a Support Vector Machine classifier. We conclude that machine learning classifiers can generate accurate wound care decisions on lower extremity chronic wounds, an important step toward objective, standardized wound care. Higher decision-making accuracy was achieved by leveraging clinical comments from wound experts.

Implementation of a Pressure Ulcer Prevention System would prevent pressure ulcers, ease workload on caregivers, enabling patient treatment and monitoring outside a hospital setting, and reduce health care costs. Accurate measurement of pressure is an important criteria in order to achieve the above said goals. A challenge associated with using Force-Sensing Resistors (FSRs) as a pressure sensor is the part-to-part variability of up to ±25%. This paper presents a novel modeling technique for correcting force sensor nonidealities, without requirement of prior knowledge of material parameters, and enabling measurement accuracies of ±2% over a pressure range of 1N to 5N.

The system described in this paper is intended for prevention of pressure ulcers by alerting the patient or caregiver to a potentially harmful level of contact pressure that could cause irreversible tissue damage. Experimental results are presented demonstrating pressure measurement techniques on a euthanized animal model. A Sprague-Dawley rat was euthanized and an alloy sheet steel disc was implanted under the latissimus dorsi muscle. Pressure was applied using various Neodymium Iron Boron alloy magnets. The data were communicated wirelessly to a base station. Measurement results show that applied contact pressure can be measured in real time, which can eventually alert a caregiver to a condition requiring intervention.

Implementation of a Pressure Ulcer Prevention System would reduce health care costs by improving pressure ulcer prevention, enabling patient treatment, monitoring outside a hospital setting, and easing workload on caregivers. In order to achieve the above said goals, it is important to be able to measure local skin pressure accurately. Disadvantages of a voltage-based resistance measurement technique include the need for a steady reference voltage and accurate ADC, each of which introduces additional error and power dissipation. This paper presents a novel interfacing technique for resistive force sensors, allowing the determination of resistance using a time-based measurement approach.

Methods: A retrospective review of patients with large midline abdominal hernia treated using component separation technique from 2009 to 2013 at General Surgery Department of Kipshidze Central University Hospital was performed. The scoring criteria were wound complications (infection, hematoma, seroma, scin necrosis, secondary healing), time to return to work/normal activities and recurrent hernia. The mean follow-up time was 21 months.

This paper describes system design issues involved in the development of a wearable wireless sensor system for continuous monitoring of skin pressure, temperature, and relative humidity. The system is intended for prevention of pressure ulcers (bedsores), and would alert a patient or caregiver to a potentially harmful level of contact pressure or adverse microclimate that could cause tissue damage. Implementation of this system would reduce health care costs by improving pressure ulcer prevention, enabling patient treatment and monitoring outside a hospital setting, and easing workload on caregivers.

A flexible, wearable sensor patch for simultaneous monitoring of local skin pressure and temperature is described. Measurement can be collected for a period of time extending over several hours, suitable for monitoring in a clinical setting, for example during surgery, in the home, or in a long-term care facility. Experimental results are presented demonstrating pressure and temperature measurement at multiple locations on an anesthetized animal during a seven hour surgical procedure.

The purpose of this primer is to provide the clinical surgeon with a survey overview of the basic biochemistry of collagen and the methods and rationale of collagen cross-linking in the processing and preparation of bioprosthetics for surgical implantation. The author highlights the critical biologic factors, such as strength over time, integration, and rate, and type of remodeling, that are to an extent controllable by the cross-linking of collagen tissues so that clinicians may be better capable of understanding differences among the devices, which may be more applicable to their clinical indications.

Transplantation of human skin on immunodeficient mice that support engraftment with functional human immune systems would be an invaluable tool for investigating mechanisms involved in wound healing and transplantation. Nonobese diabetic (NOD)-scid interleukin-2 gamma chain receptor (NSG) readily engraft with human immune systems, but human skin graft integrity is poor. In contrast, human skin graft integrity is excellent on CB17-scid bg (SCID.bg) mice, but they engraft poorly with human immune systems.Human skin grafts transplanted onto immunodeficient NSG, SCID.bg, and other immunodeficient strains were evaluated for graft integrity, preservation of graft endothelium, and their ability to be rejected after engraftment of allogeneic peripheral blood mononuclear cells.Human skin transplanted onto NSG mice develops an inflammatory infiltrate, consisting predominately of host Gr1(+) cells, that is detrimental to the survival of human endothelium in the graft. Treatment of graft recipients with anti-Gr1 antibody reduces this cellular infiltrate, preserves graft endothelium, and promotes wound healing, tissue development, and graft remodeling. Excellent graft integrity of the transplanted skin includes multilayered stratified human epidermis, well-developed human vasculature, human fibroblasts, and passenger leukocytes. Injection of unfractionated, CD4 or CD8 allogeneic human peripheral blood mononuclear cell induces a rapid destruction of the transplanted skin graft.NSG mice treated with anti-Gr1 antibody provide a model optimized for both human skin graft integrity and engraftment of a functional human immune system. This model provides the opportunity to investigate mechanisms orchestrating inflammation, wound healing, revascularization, tissue remodeling, and allograft rejection and can provide guidance for improving outcomes after clinical transplantation.

The role of proteases in chronic wounds has been the subject of many investigations in recent years. These studies have reported biochemical differences between chronic and acute wound fluids and have shown that elevated levels of proteases, in particular the matrix metalloproteinases are abundant in chronic wounds. While this has led to the hypothesis that the chronic wound environment is hostile and not conducive to wound repair, it is still unknown whether this is due to a direct or indirect defect in protease regulation or their inhibitors. We hypothesize that an excess of proteases, specifically the serine proteases present in chronic wounds, are primarily responsible for this hostile wound environment. These proteases degrade endogenous growth factors, reducing their efficacy and delaying healing. In this study, fluid and tissue from chronic and acute wounds were collected over a 24-hour period. Using ELISA, samples were assessed for protease activity (specifically elastase and typsin-like enzymes), their inhibitors and growth factors. Our results show that serine proteases, predominantly elastase, were significantly elevated in the chronic wound fluids. The serpins designed to control these proteases were not up-regulated when compared to the acute controls, resulting in excessive proteolytic activity. An increase in serine protease production without an increase in their serpins is thought to result in a reduction in growth factors, an effect, which was also observed in the chronic wound samples. This work indicates that there is an imbalance in the ratio of inhibitor to enzyme, due to an up regulation of protease production in chronic wounds. We also conclude that misregulation of serine proteases may be responsible for the observed excessive degradation of the extracellular matrix and growth factors in these chronic wounds.

Rigid metal plates are a promising alternative to wires for reapproximating the sternum after open-heart surgery due to their potential ability to reduce motion at the wound site and thereby reduce the likelihood of post-operative healing complications. Despite initial clinical success, the use of plates has been limited, in part, by insufficient knowledge about their most effective placement. This study compares the ability of five plate configurations to provide stable closure by limiting sternal separation. Commercially available x-shaped and box-shaped plates were used and combinations of parameters (plate type, location, and number of plates) were investigated in vitro. Lateral distraction tests using controlled, uniform loading were conducted on 15 synthetic sterna and the distractions between separated sternum halves were measured at seven locations. Distractions at the xiphoid, a critical region clinically, varied widely from 0.03 +/- 0.53 mm to 4.24 +/- 1.26 mm depending on all three plate parameters. Of the configurations tested, three x-shaped plates and one box-shaped plate resisted sternal separation most effectively. These results provide the first comparison of plate configurations for stabilizing a sternotomy. However, basic mechanical analyses indicate that sternal loading in vivo is non-uniform; future studies will need to accurately quantify in vivo loading to improve in vitro test methods.

Background The incidence of severe sternal wound complications in high-risk cardiac patients presents a significant need for more stabile sternal fixation techniques after median sternotomy procedures. Rigid metal plates, a potential alternative to wire fixation, are thought to promote faster sternal healing by reducing motion at the wound site. The goal of this study was to compare the stability provided by commercially available sternal plates with standard wires using an in vitro model. Methods Lateral distraction tests were conducted on bisected polyurethane sternal models fixed with either a standard 7 wire configuration (n = 5) or a 3 plate configuration (n = 3). To assure controlled loading, the sternal models were attached to a computer-controlled test machine by a novel tethering system that distributes the total force (180N) equally to eight locations on the sternum. Stability was defined as the ability to restrict sternal separation at seven locations along the midline quantified using digital image analysis. Results Our results indicate that rigid plate fixation significantly reduced lateral motion relative to wire fixation. The lower sternal region most noticeably benefited from plate fixation as the splaying observed for wire fixation was reduced. Conclusions Under these loading conditions, plating increased stability at the midline compared to wires; this increased stability may facilitate the recovery of high-risk patients undergoing cardiac operation. To enhance in vitro testing methods, future studies should incorporate additional in vivo loading conditions applied to the sternum. Alternate plating configurations should also be examined to further increase stability.

Frontal sinus fractures have traditionally been repaired through a bicoronal approach. This incision provides a wide exposure, but is not without complications, particularly in the patient with or at risk for hairline recession. We present a series of 15 patients who underwent open reduction and internal fixation of anterior table frontal sinus fractures through a frontalis rhytid forehead incision and their results based on the scar appearance, forehead contour, frontalis function, sensation and fracture reduction. Paresthesias cranial to the incision in the supraorbital or supratrochlear distribution were noted in 12 of the 15 patients with resolution in all except 1 patient who did not regain sensation at 4 months follow-up. In all patients, satisfactory forehead contour and fracture reduction were achieved, as were scar appearance and frontalis function at 4 months follow-up. We thus recommend this approach in the treatment of anterior table frontal sinus fractures, with special consideration for the patient with or at risk for anterior hairline recession.

Background: Barbed sutures were developed to reduce operative time and improve security of wound closure. Objective: The authors compare absorbable barbed sutures (V-Loc, Covidien, Mansfield, Massachusetts) with conventional (smooth) absorbable sutures for soft tissue approximation. Method: A prospective multicenter randomized study comparing barbed sutures with smooth sutures was undertaken between August 13, 2009, and January 31, 2010, in 241 patients undergoing abdominoplasty, mastopexy, and reduction mammaplasty. Each patient received barbed sutures on 1 side of the body, with deep dermal sutures eliminated or reduced. Smooth sutures with deep dermal and subcuticular closure were used on the other side as a control. The primary endpoint was dermal closure time. Safety was assessed through adverse event reporting through a 12-week follow-up. Results: A total of 229 patients were ultimately treated (115 with slow-absorbing polymer and 114 with rapid-absorbing polymer). Mean dermal closure time was significantly quicker with the barbed suture compared with the smooth suture (12.0 vs 19.2 minutes; P < .001), primarily due to the need for fewer deep dermal sutures. The rapid-absorbing barbed suture showed a complication profile equivalent to the smooth suture, while the slow-absorbing barbed suture had a higher incidence of minor suture extrusion. Conclusions: Barbed sutures enabled faster dermal closure quicker than smooth sutures, with a comparable complication profile. Level of Evidence: 1 ![Graphic][1] [1]: /embed/inline-graphic-1.gif

BACKGROUND Seroma formation is a well-recognized complication associated with many operative procedures. Despite its ubiquity, a lack of definitive scientific understanding of the etiology, natural history, and biochemistry of seromas remains. We endeavored to create and examine seromas in a rat model in the setting of commonly used biologic implants and to examine the role of quilting sutures/mechanical fixation in mitigating seroma development. METHODS Female Sprague-Dawley rats were assigned to either Quilting or Nonquilting groups then subdivided into one of 3 porcine dermal implant groups (Permacol Surgical Implant, Strattice Reconstructive Tissue Matrix, or XCM Biologic Tissue Matrix) or control group. A 5-cm midline back incision was made, the skin reflected and the latissimus dorsi muscle resected bilaterally. Implants were sutured into the surgical bed using a running suture. The skin of nonquilted rats was closed with a running subcuticular suture. Quilted rats underwent placement of absorbable quilting sutures spaced 2 cm apart between the skin and underlying implant or muscle before skin closure. Postoperatively, rats were monitored for seroma formation with fluid aspirated as needed. At 28 or 90 days, rats were euthanized. Seroma and implants were examined grossly and under light microscopy. RESULTS Of nonquilted rats, 42/54 (78%) developed seromas compared with 19/46 (41%) of quilted rats (P < 0.05), defined by bursa cavity present at necropsy. When a biologic implant was present, 28/35 (80%) of nonquilted rats developed seromas compared with 12/33 (36%) of quilted rats (P < 0.05). In the control group, 14/19 (74%) of nonquilted rats developed seromas compared with 7/13 (54%) of quilted rats. This difference was not statistically significant. Bursa presence was confirmed histologically in all cases, with no difference in bursa character seen between groups. CONCLUSIONS This study confirms a reliable rat model of seroma formation, with most of the rats exhibiting at least subclinical seromas. There was no difference in seroma formation rate in the presence of biologic implants, and no differences in bursa character between implants. Mechanical fixation with quilting sutures decreased seroma rate significantly in all subgroups. All rats with seromas at necropsy had histological evidence of a bursa with no difference in appearance between groups.

Although the clinical experience with calcium alginate has been generally good, well-controlled studies examining the effect of such dressings on the processes of wound healing have not been conducted. The healing of cutaneous ulcers requires the development of a vascularized granular tissue bed, filling of large tissue defects by dermal regeneration, and the restoration of a continuous epidermal keratinocyte layer. These processes were modeled in vitro in the present study, utilizing human dermal fibroblast, microvascular endothelial cell (HMEC), and keratinocyte cultures to examine the effect of calcium alginate on the proliferation and motility of these cultures, and the formation of capillarylike structures by HMEC. This study demonstrates that the calcium alginate tested increased the proliferation of fibroblasts but decreased the proliferation of HMEC and keratinocytes. In contrast, the calcium alginate decreased fibroblast motility but had no effect on keratinocyte motility. There was no significant effect of calcium alginate on the formation of capillarylike structures by HMEC. The effects of calcium alginate on cell proliferation and migration may have been mediated by released calcium ions. These results suggest that the calcium alginate tested may improve some cellular aspects of normal wound healing, but not others.

Immunodeficient mice engrafted with human HSCs support multidisciplinary translational experimentation, including the study of human hematopoiesis. Heightened levels of human HSC engraftment are observed in immunodeficient mice expressing mutations in the IL2-receptor common γ chain (IL2rg) gene, including NOD-scid IL2rγnull (NSG) mice. Engraftment of human HSC requires preconditioning of immunodeficient recipients, usually with irradiation. Such preconditioning increases the expression of stem cell factor (SCF), which is critical for HSC engraftment, proliferation, and survival. We hypothesized that transgenic expression of human membrane-bound stem cell factor Tg(hu-mSCF)] would increase levels of human HSC engraftment in nonirradiated NSG mice and eliminate complications associated with irradiation. Surprisingly, detectable levels of human CD45+ cell chimerism were observed after transplantation of cord blood–derived human HSCs into nonirradiated adult as well as newborn NSG mice. However, transgenic expression of human mSCF enabled heightened levels of human hematopoietic cell chimerism in the absence of irradiation. Moreover, nonirradiated NSG-Tg(hu-mSCF) mice engrafted as newborns with human HSCs rejected human skin grafts from a histoincompatible donor, indicating the development of a functional human immune system. These data provide a new immunodeficient mouse model that does not require irradiation preconditioning for human HSC engraftment and immune system development.

BACKGROUND: Plastic surgeons are faced with increasing numbers of patients presenting for insurance-covered skin excision procedures following bariatric surgery. Panniculectomy for symptomatic relief of rashes is commonly performed, but an isolated infraumbilical amputation-type panniculectomy is a highly unaesthetic procedure, leaving many patients deeply dissatisfied. It may be also fraught with complications due to large incisions and potential for dead-space. In these patients, many surgeons avoid the fleur-de-lis panniculectomy, despite the body contour aesthetic advantage, because of increased time, more scarring, and a perceived increase in complications. METHODS: This is a retrospective chart review of 130 consecutive postbariatric surgery patients who had panniculectomy over a 2-year period at our institution. RESULTS: A total of 30 patients underwent a traditional panniculectomy and 100 patients had a fleur-de-lis panniculectomy. Mean weight loss from bariatric surgery to panniculectomy was 58.2 kg, with an average body mass index (BMI) of 30. Fifty-seven patients had additional procedures performed at the time of panniculectomy. Twenty-two patients (17%) had complications, with 5 in the traditional group (17%) and 17 in the fleur-de-lis group (17%) (P = 1.0). Six males (40%) had more complications compared with 18 females (15.7%) (P = 0.034). Patients with BMI

The purpose of this study was to compare inflammatory responses, tissue integration, and strength of the acellular dermal collagen matrices AlloDerm(®)* Regenerative Tissue Matrix, Permacol™**Surgical Implant (Permacol), and CollaMend™*** Implant in a rat model for ventral hernia repair.Rats were randomized into four groups and abdominal wall defects repaired with an inlay graft of AlloDerm, Permacol, or CollaMend. Rats were sacrificed at six time points and the defect area was removed and analyzed for tissue integration and physical strength.Variable cell infiltration was seen for the three implant groups. At of the all time points examined, cellular infiltration was most rapid in the AlloDerm implants and slowest for CollaMend. At 14 days, significant cell infiltration along with putative blood vessel formation was observed for AlloDerm, while Permacol implants exhibited a moderate level of infiltration. Very few cells penetrated CollaMend implants at 2 weeks. Cells had reached the center of the Permacol implants by 1 month, whereas CollaMend implants were encapsulated with a loose coat of disconnected cells, with very few cells infiltrating past the surface. At 6 months, AlloDerm and Permacol had evidence of cell penetration throughout the implants, while the CollaMend samples exhibited limited infiltration. Animals for each implant developed seromas: AlloDerm 40%, Permacol 33%, and CollaMend 83%. Mechanical testing revealed that AlloDerm at 6 months showed the lowest tensile strength, CollaMend the highest, and Permacol an intermediate level.The three biologics exhibited different patterns and rates of cellular and vascular permeation in our rat model. AlloDerm implants exhibited the most rapid and extensive cellular infiltration, followed by Permacol. However, on gross examination, the AlloDerm implants thinned significantly by 6 months. In contrast, the Permacol and CollaMend implants appeared to be largely intact.

No current method of flap monitoring is ideal for use in all types of free tissue transfers. No method provides objective, easily communicated data that is identical in all types of transfers. In particular, reliable monitoring of buried transfers has proved difficult with available methods. The rat anterior thigh flap based on the external iliac vascular pedicle was introduced by us as a model of deep free tissue transfer. Four sets of 10 flaps were raised in the following groups: Group A (control), Group B (arterial occlusion), Group C (venous occlusion), and Group D (arterial and venous occlusion). Postoperative muscle flap pH was measured with a micro-pH electrode (1.2 mm) and correlated with arterial blood gas. Results showed excellent correlation of flap and serum pH over time (mean flap pH, 7.28; mean serum pH, 7.30). Arterial occlusion produced a rapid drop in flap pH of 0.66 pH units at 1 hour. Venous occlusion pH drop was 0.27 pH units at 1 hour, 0.53 pH units at 3 hours. Arterial and venous occlusion produced a pH drop of 0.55 pH units at 1 hour. The most rapid rate of pH drop occurred immediately after vessel occlusion. We have used continuous pH monitoring in 21 free tissue transfers for up to 84 hours after surgery. PH values remained constant in each transfer (range, 7.20-7.50; grand mean, 7.35). There was one flap failure among the monitored group of flaps, which was predicted by pH drop before loss of Doppler pulse.(ABSTRACT TRUNCATED AT 250 WORDS)

We hypothesize that Permacol™ may allow controlled integration over time while providing long-term mechanical stability and native tissue remodeling. The purpose of this report is to investigate these properties in an explanted piece of Permacol™ after 2 years in vivo. A 62-year-old female presented with a complex abdominal wall history having undergone a transverse rectus abdominis musculocutaneous (TRAM) flap breast reconstruction 10 years ago, followed by an abdominal wall repair with Marlex™ mesh for weakness 3 years later. Two years ago, she developed an abdominal bulge repaired with a Permacol™ overlay. Twenty-three months postoperatively, she presented with abdominal distension. Computed tomography (CT) scanning demonstrated a fluid collection behind the Permacol™. She underwent incision and drainage of the hematoma/bursa and quilting repair of the abdominal wall. A 1 × 6-cm Permacol™ section was resected as part of closure. Histology, immunohistochemistry, and mechanical testing of the Permacol™ explant were performed. Histology showed fibroblast and blood vessel ingrowth with no cellular infiltrates reflective of inflammation. Immunohistochemistry for human-specific collagen types I and III and elastin detected staining throughout. Sections stained with non-specific control antibody exhibited no discernable staining. Elastin highlighted blood vessels. Native Permacol™ had a breaking strength of ~20 N, while for explanted Permacol™, it was ~33 N. Permacol™ maintained durability while allowing vascular ingrowth without residual inflammation. Explant demonstrated integration with human collagen and elastin remodeling throughout. Increase in mechanical strength may reflect newly synthesized collagen and elastin. These histologic findings and clinical result support the use of Permacol™ in complex abdominal wall reconstruction.

The authors present a case of free vascularized transfer of the tibial bone as an osteomyocutaneous flap based on the posterior tibial vessels. A 42-year-old man presented with severe crush injury to bilateral legs. The left tibial bone and soft tissue defect required reconstruction with an osteomyocutaneous free flap. Since the contralateral leg was traumatically amputated at the level of the ankle, a decision was made to harvest a free tibial osteomyocutaneous flap with below-knee-amputation completed. The transfer was achieved successfully with complete survival of the flap and bony union. This report describes the technical and healing aspects of such a unique transfer which may rarely be indicated.

The goal of this study is to compare the performance of currently available screw types and configurations for rigid sternal fixation. Bone fixation plates were attached to osteoporotic human sternum with cortical or cancellous screws in either a unicortical or bicortical manner. The plates were cyclically loaded transversely (0–50N at 2Hz) for 15,000 cycles; the resulting lateral screw displacement was measured continuously. Bicortical attachment allowed significantly lower initial displacement than unicortical (p = 0.015), whereas cortical screws allowed significantly lower displacement than cancellous screws after long term cycling (p = 0.039). These initial findings indicate that both screw type and cortical purchase are important parameters in the design of a rigid plating system for sternal closure. Cortical screws appear to be more applicable to the osteoporotic sternum, as the cortical shell regions support more screw purchase than the degenerated cancellous part, and bicortical screw purchase appears to decrease screw loosening.Copyright © 2009 by ASME

Negative pressure wound therapy (NPWT) is described as it is used in the treatment of an infant burn victim. This case highlights the ability and techniques used to maintain an airtight dressing seal in the perirectal region. Use of this dressing type post-skin grafting allowed for 100% graft adhesion and no bacterial contamination despite close proximity to the rectum. Favorable experience and outcome with this patient are strong indicators that NPWT should be considered as a viable treatment in pediatric populations and that situations where body contour or fluids may make NPWT difficult to administer should not be a deterrent to therapy.

The goal of this study was to compare the performance of cancellous and cortical screws for plate and screw fixation of the sternum. Pelvic bone plates were fixated to osteoporotic sternum in both unicortical and bicortical configurations and then loaded transversely (0–50N at 2Hz) for 15,000 cycles. The resulting plate displacement was measured continuously. In the first 10 cycles bicortical screw purchase demonstrated less loosening (p=0.015), while differences between screw type was insignificant. After the 15,000 cycles, cortical screws had less loosening (p=0.039) than cancellous, while the number of cortices fixated was insignificant to loosening. These initial findings indicate that both number of cortices fixated and type of screw are both important in designing and optimized system for sternal fixation. It appears that the cortical shell regions allow more screw purchase than the osteoporotic cancellous regions, while bicortical screw purchase appears to minimize the loosening of the screws.

Current skin biopsy techniques utilizing a punch biopsy device can leave raised scars that are cosmetically unappealing. With 3.8 million procedures per year, the potential marketability of a superior device is substantial. The goal of this study is to design a novel elliptical punch biopsy device that maintains the simplicity of existing products while minimizing scarring. Mechanical testing was performed on porcine skin to determine the force required to breach the dermal layer using a single #11 scalpel blade (comparable to the excision biopsy technique), the traditional biopsy punch, and a novel blade design. The force required to penetrate the skin using the novel design (81.72 N) prototype was considerably higher than the single #11 blade (1.89 N–2.42 N) as well as the punch biopsy (4.61 N). Initial force data and mathematical analysis has resulted in a final blade design that requires less force than the initial prototype and includes fail-safes to prevent excessive depth of penetration. Clinicians will ultimately test these devices, and their feedback will be used to create a final production design. Finally, a proposed mass manufacturing technique was created.

The development of more effective fixation devices for reapproximating and immobilizing the sternum after open-heart surgery is limited by current methods for evaluating these devices. In particular, precise emulation of in vivo sternal loading has not been achieved in controlled model systems. The present study is an initial effort to determine the in vivo loading parameters needed to improve current in vitro and in silico (computational) models. Towards this goal, the direction, magnitude, and distribution of loading along a midline sternotomy were characterized in a porcine model. Two instrumented plating systems were used to measure the forces across the bisected sternum in four anaesthetized Yorkshire pigs during spontaneous breathing, ventilated breathing, and coughing for four treatments: live, cadaveric, embalmed, and refrigerated. Changes in forces incurred by death and embalming were also investigated to evaluate the potential applicability of cadavers as models for testing sternal fixation devices. The magnitudes of the respiratory forces in three orthogonal directions ranged from 0.4Nto43.8N, many fold smaller than previously estimated. Dynamic forces were highest in the lateral direction during coughing and low in all directions during normal breathing. No significant differences in force were found between the four treatments, most likely due to the unexpectedly low magnitude of forces in all groups. These results provide the first measurements of in vivo sternal forces and indicate that small cyclic fatigue loads rather than large quasistatic loads should be applied in future model systems to best evaluate the mechanical performance of fixation devices.

Approximately 15,000 Americans suffer complications associated with inadequate sternal fixation after open-heart surgery each year [1]. Although alternative fixation methods exist, limitations of current device evaluation systems have led to uncertainty about the relative increase in stability that these novel devices provide, thereby diminishing their widespread clinical use. Sternal closure techniques are typically evaluated in situ where estimated sternal forces (180–400N) are applied to an intact chest [2] or in vitro on isolated sternal models [3]. The mechanical stability afforded by each technique is quantified as the resultant separation along the bisected sternal midline. This displacement is assumed to reflect micro-motion that would occur at the wound site under physiological loading, a critical factor during bony healing [4]. However, the loading in these studies is hardly physiological; it is generally simplified to a single direction and applied quasistatically to only a few discrete locations along the sternum without regard for the in vivo distribution of forces. It is also unclear whether the transfer of loads from sternum to fixation device during in situ tests [5](cadavers) accurately reflects loading in vivo due to the potential effects of rigor mortis and/or embalming. To improve the accuracy of current in situ and in vitro sternal fixation test methods it is essential to advance our knowledge of in vivo dynamic multi-directional sternal loading.Copyright © 2007 by ASME

Ischemic preconditioning has been shown to improve survival of cutaneous flaps. The authors examined the effect of remote ischemic preconditioning (RIPC) on phosphorylation of p38 MAP kinase and related the results to flap survival. Female Wistar rats had 8 x 12-cm abdominal adipocutaneous flaps raised on the medial branch of the superficial epigastric artery. Controls (Group 1) had the flap elevated and the pedicle clamped for 3 hr, then closed with a sheet of plastic between the flap and abdominal wall. Group 2 animals had RIPC by tourniquet on the contralateral hind limb before the flap was dissected. Group 3 animals mimicked Group 2 and also had an infusion of the nitric oxide blocker, N-nitro-L-arginine methyl ester (L-NAME) 5 min prior to the RIPC. Group 4 had the flap elevated prior to the RIPC. All groups except Group 1 had 10 min of RIPC with 30 min of reperfusion, then 3 hr of ischemia. Tissue samples were taken at the distal margins of the flaps before preconditioning and 30 min after preconditioning for detection of p38 MAP kinase and phosphorylated p38 MAP kinase (pp38 MAP kinase). Group 2 flaps (RIPC before flap elevation) exhibited better flap tissue survival and had well-defined phosphorylation of p38 MAP kinase 30 min post RIPC, when compared to the other groups. Pre-infusion with the nitric oxide blocker (Group 3) before RIPC blocked the survival advantage conferred by preconditioning and diminished the phosphorylation of p38 MAP kinase. Tissue from all groups showed very little phosphorylation of p38 MAP kinase following 3 hr of ischemia. Thus, increased tissue survival is correlated with elevated levels of p38 MAP kinase phosphorylation following RIPC. This effect is inhibited by blockade of nitric oxide. Modulation of the p38 MAP kinase pathway may represent a protection pathway for ischemic preconditioning.

Peripheral edema causes swelling in extremities that often indicates the presence of a serious medical condition. Currently, clinicians visually observe fluctuations in edema symptoms to assess edema severity. The subjective nature of these assessments hinders clinicians from accurately communicating a patient's condition to other medical professionals and leads to inconsistencies in medical treatment. To eliminate subjectivity in edema measurement, we developed a handheld device that uses a manually depressed probe to objectively measure the depth of pitting from edema and the force required to depress the tissue, which correlate directly to edema severity. Clinicians can collect these values from the device over time to monitor a patient's progress and improve the accuracy of medical diagnosis.

Background The heterodigital artery island flap is a popular method of reconstruction for finger defects. Postoperative venous congestion is a common problem. Methods The authors present a technique to augment venous drainage of the flap. Briefly, the flap is harvested along with a dorsal vein that is then anastomosed to a recipient vein in an end-to-end fashion, after flap transfer and insetting. Using this technique, seven patients were operated on, ranging in age from 5 to 35 years (average age, 23 years). Results All flaps survived with no postoperative flap congestion, fully satisfying the reconstructive requirements. By this modification, skeletonization of the digital artery of the flap pedicle is safe if that approach is preferred, since there is no need to harvest periarterial fat for venous drainage. Conclusions Providing good harmony with conventional methods and microsurgery, inclusion of a vein with the heterodigital artery island flap allows a more reliable and safer reconstructive choice for finger defects. Such a modification converts the unconventional venous circulation of the heterodigital artery island flap to a more physiologic one.

Considering both its unique structural and functional properties, the reconstruction of the penis is still a challenging problem in reconstructive surgery. Reconstruction may be required in many situations, including traumas, congenital abnormalities, and female-to-male transsexual surgery. Currently, the only natural reconstructive method for the penis is its microvascular reattachment in amputation cases. In all other situations, and in nonreplantable amputations, there is no alternative but to reconstruct the penis using autologous tissues to create the most similar substitute, hoping for a possible allogeneic transplantation in the future. There are many unresolved issues and unanswered questions related to functional recovery after replantation of the penis. In this study, to overcome these drawbacks and to guide and show the feasibility of allogeneic transplantation of the penis in humans in the future, we describe a penile composite tissue flap based on the internal pudendal artery and its autotransplantation in an economical animal species. Fifty adult male Sprague-Dawlcy rats weighing 400 to 500 g were used. In 20 rats, the vascular anatomy of the male perineal region was determined by anatomic dissections. Based on this anatomic study, the penile composite flap was created based on the internal pudendal vessels. In 10 rats, the penile flap was raised as an island flap based on its vascular pedicle and replaced in situ. In 10 rats, distant flap transfer was accomplished to determine the feasibility of the flap being transferred as a free flap and to demonstrate the viability of the flap components in a heterotopic region. For this purpose, the flap was transferred to the groin region performing anastomoses between internal pudendal vessels and superficial epigastric vessels. In the control group (n = 10), while the same surgical procedure was performed, the flap was transferred to the groin region but no anastomosis was performed. The procedure required approximately 3 to 4 hours of operating time in the free flap group. Five of the animals died in the early postoperative days, while all others survived. Direct observation and microangiography were used to assess the viability of the flaps. On the basis of direct observation on the seventh postoperative day, all the pedicled flaps survived completely. In the free-flap group, all but I of the vascularized flaps showed complete survival, whereas all the nonvascularized flaps completely necrosed. The authors conclude that the penile flap of the rat offers the following advantages: (1) the composite tissue flap is harvested from a small animal species, (2) the flap is an exact representation of the clinical original penile composition, (3) it can be transferred as a free flap without the need for an isogeneic animal, (4) the vascular pedicle is consistent and allows for microvascular anastomoses. The flap will provide a means for future physiological studies, especially for replantation cases. The feasible autotransplantation of the penile flap with successful results will also guide researchers towards the future allogeneic transfer of the penis in humans.

Free-vascularized fibular flaps have been associated with high risks of graft fracture when used for the reconstruction of discontinuous fractures in the tibia. Plastic surgeons have suggested the use of a free-vascularized femur flap (wedge-shaped bone segment with connected vasculature) from the anterolateral shaft of the contralateral femur as an alternative. The goal of this study was to determine the femur flap size required to provide equivalent support as a fibula flap and to assess the need for intramedullary rod support of the femur following removal of the bone segment. Three-point bending tests were conducted on fibula and femur flaps to characterize the mechanical properties of the bone segments. The average fibular yielding load was 550/spl plusmn/175 Newtons. To match this load, 35% of the femur's circumference must be used. Intact femurs and femurs with 35% flaps removed were tested in compression while being oriented in the anatomical position to simulate the natural compression and beading moments in the femoral diaphysis. The intact femurs failed at 840/spl plusmn/297 lbs, while the femurs with the 35% flap removed withstood 810/spl plusmn/235 lbs. In conclusion, 35% of the femoral circumference is needed to provide flaps that are equivalent to that of a fibula. The removal of the 35% flap decreases the average maximum strength of the femur, however, the decrease is not statistically significant due to the large standard deviation values. Ongoing analyses of local strain data are being performed to determine whether the procedure requires fixation of the femur.

Median sternotomy, a procedure required for open-heart surgery, cardiac valve replacement and coronary bypass surgery, is the most commonly used surgical approach in cardiothoracic surgery. Complications associated with the traditional use of stainless steel sutures for sternal closure lead to poor sternal healing, sternal separation and dehiscence in 0.5 to 2.5% of all cases. Sternal dehiscence leads to discomfort, mediastinitis, osteomyelitis, and chronic sternal instability, and it is associated with a 10-40% mortality rate. Improving the mechanical stability of sternal fixation devices will facilitate better sternal healing and decrease the likelihood of complications associated with medial sternotomy. Based on healing of long bones, it has been suggested that rigid fixation devices promote faster sternal healing while reducing the likelihood of post-operative complications. Although metal plates are currently being used clinically to provide stable sternal fixation, no mechanical data has been published to support the assertion that plates provide a more rigid fixation than wires. Our ultimate goal is to determine the optimal plating configuration for rigid fixation in terms of the location, type, and number of metal plates. The purpose of this preliminary study was to determine the stability of fixation of a sternum following midline sternotomy using three metal plates.